Automatically discharging gripper device

ABSTRACT

Gripper provided with an arm, which arm is resilient and can be closed by a spring, an axis provided with locking means being coupled with a pivotable arm, which via a resilient stretchable link is connected with a further pivotable arm and a rectilinear working spring device is acting upon one of the said pivotable arms.

United States Patent Mosterd 1 Nov. 21, 1972 [54] AUTOMATICALLY DISCHARGING [56] References Cited GRIPPER DEVICE UNITED STATES PATENTS l [72] Imam g zg gfgg ffi 1 7 3,207,548 9/1965 Moskopf et al ..294/104 3,228,249 l/l966 OBrien ..294/50.8 X [22] Filed: June 18, 1971 Primary Examiner-Evon C. Blunk [21] Appl' 154477 Assistant Examiner-Johnny D. Cherry Attorney-Larson, Taylor & Hinds [30] Foreign Application Priority Data I [57] ABSTRACT June 23, 1970 Netherlands ..7009235 Gripper provided with an arm, which arm lS resilient [52] U S Cl 294/86 R 294/] R 294,104 and can be closed by a spring, an axis provided with 294/99 locking means being coupled with a pivotable arm, 51 I t Cl B25) 5/12 which via a resilient stretchable link is connected with R 99 S a further pivotable arm and a rectilinear working spring device is acting upon one of the said pivotable arms.

5 Claims, 6 Drawing Figures PATENTEU I973 3.703.309

sum 1 UF 3 lNVENTOR JACOB H. MOSTERD aLSQQ; 3

ATTORNEYS PATENTED NOV 2 I I972 SHEET 2 BF 3 INVENTOR JACOB H. MOSTERD 0 3156 3 ATTORNEYS PATENTEUNHYZI m2 3.703.309

' sum 3 0-? 3 FIG. 3A FIG 3B lNVENTdR JACOB H. MOSTERD ATTORNEYS AUTOMATICALLY DISCHARGING GRIPPER DEVICE The invention relates to a gripper provided with a movable gripper arm, which arm is rotatable about a rotatable shaft, said rotatable shaft being coupled with a control member, said control member being capable of cooperating with locking means for locking said control member in a first position (the closed position) in which the gripper is closed, spring means exerting a mechanical bias to the control member and the gripper arm to urge said gripper arm towards a second position, in which the gripper is open, and further spring means allowing the gripper arm to move in the direction towards the second position contrary to the spring action of said further spring means.

Although a gripper of this type works well a number of disadvantages proved to be present in practice. First of all assembling appears to require relatively much work. Furthermore, the number of parts is rather considerable. Also owing to this the reliability is limited and specialized workers are required for upkeeping and repairing purposes.

The invention aims at removing the above mentioned disadvantages and at providing a simpler construction, that can easier be mounted and also with very long working times gives less rise to disturbances.

Accordingly it is provided according to the inven tion, that a pivotable arm, which has been connected with the control member, is attached toan end of a resiliently stretchable coupling rod, forming the further spring means, the second end of the coupling rod being connected with a pivotable arm having a permanent rotatable shaft, said second pivotable arm being fixedly coupled with the gripper arm, and said first mentioned spring means comprising a rectilinearly working spring device, working between a fixed point and a point of one of the said pivotable arms.

Said construction can very easily be assembled, because the spring members can be manufactured as one whole construction and must be attached with their ends only. Moreover use is made of the fact that the stretchable coupling rod practically has a minimum length, too, and owing to this serves for opening the gripper.

According to a further elaboration of the invention it is provided that the two pivotable arms make together with the coupling rod the three sides of a quadrangle, which approximately is a parallelogram.

This provides a construction which takes very little room and gives a very uniform mechanical load of pivot centers. Especially with modern manufacturing, with which use is made of synthetic materials, this is an important advantage.

When applying the invention a telescope spring can advantageously be made use of for the resiliently stretchable coupling rod. A telescope spring is a member behaving as a stretching spring, but internally containing a compression spring, enclosed in a housing. This means, that with spring ruptures, if any, in many cases disturbances do not occur at once and still a reasonable working is obtained. When using tension springs serious disturbances occur at once with spring ruptures.

The same holds with respect to the rectilinear working spring device. Naturally it is for the latter also possible to directly use a compression spring.

Finally a very simple unlocking mechanism for the gripper as described above is obtained because the control member has a guide arm, which is coupled with the first'pivotable arm, said guide arm having a locking plane capable of co-operating with a latch urged into the locking position by means of gravity.

The invention is in the following elucidated by means of the drawings, in which:

FIG. 1 schematically shows a side elevation of a gripper according to the invention in combination with a weighing device of a type that can be used with an automatic sorting machine;

FIG. 2. shows a front elevation of the gripper shown in FIG. 1;,

FIGS. 3A and 38 give a section along the line III-III in the closed and the open position of the gripper respectively; and

FIGS. 4A and 4B give a bottom sight of the gripper, seen from the line IV--IV, again in the closed and the open position respectively. I

In FIG. 1 a weighing device has been indicated having a supporting frame 1, in which shaft 2 is rotatably supported, bearing a weighing beam 3. To the left in FIG. 1 the gripper generally indicated by 4 has been attached to said weighing beam by means of a pivot connection 5. At the other end of the weighing beam 3 an adjustable weight 6 is present, which is partially formed by permanent magnets 7, co-operating with a plate 8 of electrically well conducting material for damping swinging movements of the weighing beam 3. Furthermore a coupling rod 9, which at 10 is rotatably connected with the gripper 4 in such a way that the left portion of the beam 3 and said coupling rod 9 form a parallelogram guiding means, is attached to the frame 1. A shaft 11 has pivotably been mounted in the gripper, a control arm 12 being fixedly connected with said shaft 11. Said control arm bears at its end a freely pivotable roller 13 and also a locking surface 14. Herewith latch 15 can co-operate, said latch being pivotable about a shaft 16 and consisting of two arms, one of which bearing at its end a locking hook l7 and the other arm 18' hanging downwardly and being stopped by a stop member 19. A pivotable arm 20 is fixedly connected with the lower side of the shaft 11, said pivotable arm being connected at its end by means of a pivot 21 to a telescope spring 22, forming a resiliently stretchable rod coupled by means of a pivot 23 to a further pivotable arm 24, which is fixedly connected to a rotatably mounted shaft 25, to which also a gripper arm 26 has fixedly been connected. With a further pivot point 27 of the pivotable arm 20 a telescope spring 28 is connected, the other end of which has been connected to a fixed pivot 29. The construction of telescope spring is known in itself and has schematically been indicated in FIG. 4B for the telescope spring 28.

In FIGS. 3A and 4A the closed position has been indicated. Therewith it has been indicated in dotted lines, how arm 24 and gripper arm 26 by stretching telescope spring 22 can rotate a little hit counter clock wise, in order to obtain a resilient adjustment to the object retained by the gripper. The gripper is formed by finger 30 at arm 26 on the one hand and a pair of fixed pins or fingers 31 and 32 on the other hand.

The construction described works as follows:

When closing the gripper, which takes place by swinging arm 12 in FIG. 3B until it takes the position of FIG. 3A and the locking hook 17 falls behind the locking surface 14, gripper arm 26 is brought into the position of FIG. 4A. Therewith an object, not-shown, can be clamped between fingers 31 and 32 on the one hand and finger 30 of the gripper arm 26 on the other hand. In the drawing a weighing device has been indicated of the type which can be used in a sorting device. The invention is, however, not limited hereto and the particulars of the shown device, which have no connection with gripper 4 do not belong to the invention. For a good understanding of the invention it is only necessary to see that arm 18 of locking hook in FIG. 2 is swung to the left. This can, e.g., take place by having roller 13 run under a fixed guide 33 and moving the complete device supported by frame 1 into the direction of arrow 35 in FIG. 2 until arm 18 contacts a permanent stop member 34. When arm 18 and stop member 34 cooperate, book 17 is tilted up and the gripper can unhampered move, under the influence of spring 28 from the position of FIGS. 3A and 4A into that of FIGS; 3B and 48.

For returning the device to the first position, the device generally indicated by 36 is used. This device has two downwardly protruding pins 37, which are attached to a body 39 which has been mounted pivotably about the axis 38, said body being provided with two rollers 40 and 41. When the weighing device swings about shaft 2 to the right, arm 12 arrives between pins 37. By swinging the body 39 by means not shown arm 12 will therewith be taken along by the pins 37 until the locking surface 14 co-operates with the locking arm 15.

Device 36, however, does not form part of the present invention and is known in itself.

Experience has shown that by applying the invention a more reliable and cheaper gripping mechanism is obtained and that owing to the far greater surveyability, when disturbances occur, can be repaired quickly and efficaciously by non-specialized workers.

Though the invention has been described with reference to a specific sorting device with which opening the gripper interrupts the contact between the guide roll 13 and the guide 33 owing to the fact that arm 12 is swung away, it will be clear that the invention is not limited to a sorting device of this type and can always be applied when a gripper has to be closed resiliently and must be able to open under spring bias after unlocking.

What I claim is:

l. Gripper provided with a movable gripper arm, pivotable about an axis of rotation, said gripper arm being coupled with a control member, said control member being capable of co-operating with locking means for locking it in a first position in which the gripper is closed, spring means exerting a mechanical bias on the control member and the gripper arm to urge the gripper arm toward a second position in which the gripper is open, and further spring means allowing the gripper arm to move into the direction of the second position contrary to the spring action of said further springs means, characterized in that a pivotable arm 20, which is coupled with the control member 11,12, is connected to an end of a resiliently stretchable link 22,

formin the further spring m ans the second end 23 of the 11 22 being connecte with a second pivotable arm 24 having a permanent axis of rotation 25, said second pivotable arm 24 being fixedly coupled with the gripper arm 26 and the first mentioned spring means 28 comprising a rectilinear working spring device, working between a fixed point 29 and a point 27 on one of the said pivotable arms.

2. Gripper according to claim 1, characterized in that the two pivotable arms 20,24 together with the resiliently stretchable link 22 form the three sides of a quadrangle, which approximately is a parallelogram.

3. Gripper according to claim 1, characterized in that the resiliently stretchable link is a telescope spring.

4. Gripper according to claim 1 characterized in that the rectilinearly working spring device 28 is a telescope spring.

5. Gripper according to claim 1, characterized in that the control member has a control arm 12 which via the said shaft 1 1 is coupled with the first pivotable arm 20, said control arm having a locking surface, capable of co-operating with a latch 15,17,18 urged in the locking position owing to gravity. 

1. Gripper provided with a movable gripper arm, pivotable about an axis of rotation, said gripper arm being coupled with a control member, said control member being capable of co-operating with locking means for locking it in a first position in which the gripper is closed, spring means exerting a mechanical bias on the control member and the gripper arm to urge the gripper arm toward a second position in which the gripper is open, and further spring means allowing the gripper arm to move into the direction of the second position contrary to the spring action of said further springs means, characterized in that a pivotable arm 20, which is coupled with the control member 11,12, is connected to an end of a resiliently stretchable link 22, forming the further spring means, the second end 23 of the link 22 being connected with a second pivotable arm 24 having a permanent axis of rotation 25, said second pivotable arm 24 being fixedly coupled with the gripper arm 26 and the first mentioned spring means 28 comprising a rectilinear working spring device, working between a fixed point 29 and a point 27 on one of the said pivotable arms.
 1. Gripper provided with a movable gripper arm, pivotable about an axis of rotation, said gripper arm being coupled with a control member, said control member being capable of co-operating with locking means for locking it in a first position in which the gripper is closed, spring means exerting a mechanical bias on the control member and the gripper arm to urge the gripper arm toward a second position in which the gripper is open, and further spring means allowing the gripper arm to move into the direction of the second position contrary to the spring action of said further springs means, characterized in that a pivotable arm 20, which is coupled with the control member 11,12, is connected to an end of a resiliently stretchable link 22, forming the further spring means, the second end 23 of the link 22 being connected with a second pivotable arm 24 having a permanent axis of rotation 25, said second pivotable arm 24 being fixedly coupled with the gripper arm 26 and the first mentioned spring means 28 comprising a rectilinear working spring device, working between a fixed point 29 and a point 27 on one of the said pivotable arms.
 2. Gripper according to claim 1, characterized in that the two pivotable arms 20,24 together with the resiliently stretchable link 22 form the three sides of a quadrangle, which approximately is a parallelogram.
 3. Gripper according to claim 1, characterized in that the resiliently stretchable link is a telescope spring.
 4. Gripper according to claim 1, characterized in that the rectilinearly working spring device 28 is a telescope spring. 